Mosses and liverworts are small, soft plants which grow like a mat in damp and shady locations. Both have similar life cycle and reproductive organs and they lack vascular system present in developed plants. Botanically, mosses are bryophytes or non-vascular plants. Mosses are haploid, i.e., they have single set of chromosomes. Family Bryophyta includes liverworts and hornworts.
The term moss in this text encompasses all the bryophytes.
Mosses have two phases in their life-cycle. In the first phase, spores germinate to form stem, leafs and rhizoid. This upon maturity produces a zygote (fertilized egg). Zygote does not form another moss, but a slender stock with a capsule at the top. This capsule contains spores which are released to produce more moss plants.
Fossil records date the appearance of moss 350 million years ago. Mosses can become a nuisance in the lawn, plant pots, plant beds, golf courses, on driveways, on roofs etc. Mosses can grow in extreme conditions and can sustain even sub-zero temperatures. Infestation with moss may stunt the growth of other plants, increases weeding cost; may kill the grass in the lawn, and may damage roof and walls.
Many fungicides, herbicides, and inorganic salts have been used to control and/or kill moss. The commonly used inorganic salts include ammonium sulfate, ferrous sulfate, ferrous ammonium sulfate, copper sulfate etc. U.S. Pat. No. 3,964,893 cited the preparation of ferric ammonium sulfate-ammonium sulfate double salt and showed that the double salt was as effective as ferrous sulfate to control moss and its greening effect. U.S. Pat. No. 4,202,858 showed the effectiveness of copper pipe in the water container to control moss. U.S. Pat. No. 4,276,732 described a bimetallic device of copper and lead to be placed on the rooftop. With the rain water, ions of metals were released and were shown to control moss. U.S. Pat. No. 4,605,550 described a method to prepare a delayed release formulation of ferrous sulfate to kill moss. The system contained a water soluble extender, a resin and a water-insoluble extender. U.S. Pat. No. 4,936,898 claimed the preparation of powder containing atomized copper and zinc with silica clay which was shown to have moss-killing effect. In the U.S. Pat. No. 5,108,481, ferrous sulfate powder was mixed with ammonium sulfate solution and pellets were formed in a pelletizer. U.S. Pat. No. 7,368,121 described a process of controlling moss by the application of sodium percarbonate. In another embodiment, lime was added to the product to control pH of the moss and thereby constrained development of additional moss. The pH value of 3% sodium percarbonate solution is 10 to 11. The U.S. Pat. No. 7,396,801 disclosed a formulation composition containing a source of nitrogen, a non-ionic surfactant, a metal containing salt and an acidic pH adjusting agent (pH 2.5 to 5). The metal containing salt was chosen from a group consisting of copper sulfate, zinc sulfate, iron sulfate and iron chloride.
The terms—“burning moss”, “killing moss”, “eradicating moss” and “controlling moss” have been used interchangeably in this patent application and they project the same meaning.
Moss prefers to grow in an acidic soil with pH between 5.0 and 5.5. Most plants grow well in the pH range 5.8 to 7.0. Ferrous sulfate when added to water produces acidic pH (pH 1.5 to 2.2) whereas lime in water produces alkaline pH (pH 12). But, spreading lime in the lawn produces a micro-environmental pH of about 7. Lime or quicklime is calcium oxide prepared from the thermal decomposition of limestone (calcium carbonate). There are mainly two types—high calcium quicklime and dolomitic quicklime. There are hydrated forms of each. High calcium quicklime contains 0 to 5% magnesium carbonate. Dolomitic quicklime contains 35 to 46% magnesium carbonate. Calcium quicklime can absorb water to produce hydrated lime which contains 72 to 74% calcium oxide and 23 to 24% water. Under normal atmospheric conditions, only calcium oxide hydrate producing a final composition of 46 to 48% calcium oxide, 33 to 34 percent of magnesium oxide and 15 to 17 percent of water. It is termed as dolomitic hydrated lime.
In this patent application, the term “Lime” refers to calcium oxide and any of these varieties described above.
Ferrous sulfate is inexpensive, easy to use, easily available and non-toxic to the environment. It is available in different hydrate forms. These are —FeSO4.H2O (szomolnokite, relatively rare), FeSO4.4H2O (rozenite, relatively common), FeSO4.5H2O (siderotil, relatively rare), FeSO4.6H2O (ferrohexahydrite, relatively rare), and FeSO4.7H2O (melanterite, relatively common). Ferrous sulfate septahydrate (FeSO4.7H2O) was used in the experiments.
In this patent, “ferrous sulfate” reflects any of these hydrates of ferrous sulfate. The term “ferrous salt” refers to ferrous sulfate and ferrous ammonium sulfate.
Ferrous sulfate is soluble in water and there is a high probability of it getting washed away during watering of plants or rain. Ferrous sulfate has an immediate detrimental effect on moss, but if it is washed away, moss can grow back after some time. It is therefore essential to provide a steady supply of an active compound over a long period preventing further growth of moss.